Guide to configure RetroArch Online Updater to use Romarchive buildbot mirrors.
Configuration Guide
Set assets URL in Main menu → Online-updater → Updater settings → Link for downloading resources from buildbot to: http://cows.info.gf/buildbot/assets/
If there is 'Link for downloading cores from buildbot' in the same menu, remember that URL and retype it again into the same spot, but «buildbot.libretro.com» replaced to cows.info.gf/buildbot